The present invention relates to support structures for suspended walkways, suspension bridges and the like, and more particularly to a novel girder or beam construction and to a novel means of attaching an anchoring rod or hanger to the girder.
In the past, the primary box girders that underpinned suspension bridges and walkways were linked to the suspension cables which supported them by means of hangers or anchoring rods. Typically, the girders had a hollow, generally rectangular cross-sectional configuration, and the anchoring rod extended vertically therethrough. The head of the anchoring rod projected above the upper wall of the girder and was adapted to engage a cooperative connector on the suspension cable. The opposite end or tail of the anchoring rod projected below the lower wall of the girder. A stop member or members carried on the tail of the anchoring rod engaged the lower wall of the girder and carried a great deal of the load.
A major drawback to the above-described suspension assembly was the concentration of structural and applied loads on the lower wall of the girder. It was here that the support provided by a suspension cable, via the anchoring rod, was exerted on the girder. The primary site of attachment or contact for the stop member on the anchoring rod was the lower wall of the girder. Thus, if the stress in this area was sufficiently increased by overloading, material defects, degeneration or resonant vibrations, the girder could collapse inwardly from the lower wall towards the upper wall. While some of the compressive force exerted on the lower wall was diffused by the side walls of the girder, the real possibility of disaster compelled the present inventor to search for ways to distribute the load more evenly.
The present invention distributes the load on the girder more evenly by providing an additional area of contact between the girder and a stop member carried on the anchoring rod. Heretofore, the anchoring rod passed through the upper wall of the girder without being connected or secured thereto. In the present invention, as explained below, the hanger or anchoring rod is provided with a sleeve that engages the stop member at one end and the upper wall of the girder at its opposite end. Thus, the load resistance provided by the suspension cable is transmitted directly to both the upper and lower walls of the girder.